The present invention relates to a test fixture for rapidly and repeatedly measuring the dimensions of manufactured products at different specified locations on the products.
Production parts or products in an assembly line are supposed to conform with the part dimensions contained in product specifications for the parts, at least within a specified tolerance range. During the manufacture of parts, many things can. happen which cause the part sizes to vary beyond the tolerance limits. It is therefore necessary to measure the dimensions and the shape of test parts selected from the production line from time to time in order to determine if the parts still meet specifications. This is a time consuming and laborious process if done by hand with completely manual measuring devices. Moreover, the results are imprecise.
An object of the present invention is to provide a test fixture that can repeatedly, accurately and quickly take dimensional measurements off a test part at multiple locations on the part.
In accordance with the present invention, a test fixture for rapidly checking the measurements of identical parts at various points on the parts comprises: a mounting mechanism for mounting each part securely in a predetermined position; a rail or track defining a guide path that extends past selected points on the part; a movable car that is mounted on the rail for movement past the selected points on the part; and a position sensor or indicator mounted on the car for detecting the position of selected points on the part relative to selected locations on the guide path.
In the preferred invention, the part to be tested is mounted on a rigid mounting plate. A raised rail extends around at least a portion of the periphery of the part or mounting plate. A car is mounted on the rail for movement along the rail. A position sensor (indicator) attached to the car extends outward to contact the part and continuously provide a reading indicative of the relative position of the part as the car is moved on the rail around the periphery of the part. Dimensional measurements may be taken continuously or the car can be stopped at specified testing locations along the guide rail by a resilient stop mechanism such as a spring loaded ball bearing mounted to the bottom of the car that locates in machined indentations that are at specified intervals along the guide rail.
The sensor desirably is a probe that is urged outward to contact the part, such that the position of the probe is indicative of the position of the part where the probe engages the part. The probe can be aligned with the edge of the part so that the linear movement of the probe represents the position of the edge of the part. A pivot link can be attached to the probe so that the linear movement of the probe can also reflect the vertical position of the part.
The present invention comprises a testing mechanism that can accurately and rapidly measure the dimensions of a part at a number of locations on the part. This data can be stored and manipulated in a computer system so that compliance with tolerances can be continuously assured and so that any necessary modifications in the production process to maintain the product within tolerance limits can be implemented.
These and other features and advantages of the present invention will become apparent from the preferred embodiments described below and shown in the appended drawings.